MI Michell Instruments Ltd.

Pura Online Ultra-Pure Moisture Hygrometer

Name: Pura Online Ultra-Pure Moisture Hygrometer
Brand: Michell Instruments Ltd.
SKU: MI-PURA-OL

Small, rugged trace-moisture hygrometer for ultra-high-purity gas down to 1 ppbV.

ModelPura Online

SKUMI-PURA-OL

CategoryDew Point & Moisture

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Key Features

Measures down to −120°Cdp (−184°Fdp), <1 ppbV
Traceable 7-point calibration certificate
Single 4-20 mA (or 0-20 mA) output, fully user-configurable
Modbus RTU over RS485 digital output
2 programmable relay alarms
1/2" or 1/4" male VCR process connections
MiniDIN 43650 C or M12 5-pin electrical connectors
Clean-room double-bagged or industrial single-bagged packaging
Optional hazardous-area (I.S.) approved sensor variant

Overview

The Pura Online is a small, rugged pure-gas moisture transmitter and hygrometer system for trace-moisture breakthrough indication in ultra-dry purification and high-purity gas applications, measuring down to −120°Cdp (less than 1 ppb). It pairs Michell’s ceramic metal-oxide sensor with an economical local monitor for semiconductor, fibre-optic and speciality gas duties.

Working Principle

A ceramic metal-oxide sensor in a cold-drawn, electropolished stainless-steel body measures trace moisture in ultra-pure gas streams. The Pura Online monitor provides order-selectable dew-point or moisture-content scaling with a single 4-20 mA analog output and Modbus RTU over RS-485, plus 2 programmable relay alarms for process and fault conditions.

Applications

Benefits

Economical alternative to complex analytical trace-moisture analyzers
Electropolished sample path suited to ultra-high-purity gas integrity
Order-selectable scaling avoids field reconfiguration for common ranges
Sensor exchange program keeps ultra-pure gas line downtime near zero

Technical Specifications

Sensor Performance
Measurement Range	−120 to −40°Cdp (non-standard on request)
Accuracy	±1°C (−40 to −60°C); ±2°C (−60 to −100°C); ±4°C (−100 to −120°C, extrapolated)
Calibration	Traceable 7-point certificate

Monitor (Pura Online)
Range	−120 to −40°Cdp
Resolution	4 digit
Analog Output	1 x 4-20 mA or 0-20 mA, user-configurable
Digital Output	Modbus RTU over RS485
Relay Alarms	Alarm 1: 3A @250Vac SPST; Alarm 2: 5A @250Vac changeover

Electrical
Sensor Input Signal	4-20 mA
Supply Voltage	85–265 Vac or 24 Vdc
Power Consumption	60 mA max
Electrical Safety	BS/EN61010-1:2010

Operating
Operating Temp (Sensor)	−40°C to +60°C
Operating Temp (Monitor)	0°C to +50°C
Operating Pressure	10⁻⁷ Pa min; 24 MPa (240 barg) max
Flow Rate	1–5 Nl/min (sample block); 0–10 m/s direct insertion

Mechanical
Housing	316 stainless steel
Ingress Protection	IP66 (sensor, MiniDIN); IP65 (M12 sensor / monitor front)
Process Connection	1/4" or 1/2" male VCR
Weight	450 g (Premium/OEM); 180 g (Sensor version)

Downloads

Datasheet (PDF)PDF

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Frequently Asked Questions

What warranty is offered on this product?

All Tetracon-supplied instruments carry the original manufacturer warranty (typically 12–24 months) plus first-line local support from our Islamabad service centre.

Do you provide installation and commissioning?

Yes. Our manufacturer-trained engineers offer on-site installation, commissioning and startup training anywhere in Pakistan.

Are spares and calibration available locally?

Common spares are held in local stock. Calibration is available at our lab or on-site with NIST-traceable reference standards.

How long is the typical lead time?

Stocked items ship within 3–5 working days; engineered configurations typically 6–10 weeks depending on manufacturer schedule.

Request a Quote — Pura Online Ultra-Pure Moisture Hygrometer

Complete the form below and one of our engineers will respond within 1 working day with pricing and lead time. Prefer email? Contact our sales team.